Many pharmaceutically-active compounds produced by chemical synthesis are obtained and sold as mixtures of stereoisomers. However, it is often the case that only one these stereoisomers is pharmaceutically active. The contaminating enantiomer often has very poor, if any, activity or, in some instances, has unwanted physiological side-effects and shows toxicity.
Work by a number of researchers has shown that the anti-inflammatory activity of the 2-arylpropionic acids naproxen and ibuprofen is found with the (S) enantiomer. The same is true for ketoprofen, currently manufactured and sold as a racemate.
Arylalkanoic acids may be resolved by biotransformation, according to the following reaction scheme: ##STR1## wherein R' is an alkyl group, Ar is an aromatic residue and, for example, R is an aliphatic residue of 1 to 4 carbon atoms.
One particular object behind the present invention is to provide an economic route to the production of optically pure (S)-ketoprofen.